The present invention concerns a prosthetic device to be installed during below or above the knee amputations in order to widen the weight bearign area of the bone and enable bearing the body weight on the distal part of the stump.
Amputations are done today on the following indications:
1. After traumatic injury with extensive damage that did not allow for repair. PA0 2. Tumors of the bone, soft tissue, nerves and vascular system. PA0 3. Severe infection with sepsis that critically endangers life and cannot be controlled with antibiotic therapy. PA0 4. Variety of peripheral vascular diseases.
The majority of the amputations done today all over the world concern the last indication (peripheral vascular diseases).
The site of the amputations is decided according to the condition of the tissues and the blood supply, the preference being below the knee amputation if possible. The stump below the knee should be 5" or 6" long in order to enable free movement of the knee joint. The lever is stronger enabling better movement when the stump is longer.
The preferred prosthesis for below the knee amputation is the PTB-Patellar Tendon Bar prosthesis with a total contact socket. The patellar tendon tolerates the major load. The medial flare of the tibia is also utilized for weight bearing.
The preferred prosthesis for above the knee amputation is the Suction Socket Prosthesis in which the prosthesis is held on by suction and close anatomic fit.
In both of the prosthesis the pressure is not put solely on the bone and is distributed over the stump. Direct pressure on the bone is accompanied usually with pain.
The patient who underwent below the knee amputation usually uses the knee for weight bearing rather than step on the stump when moving from place to place without wearing the prosthesis. Stepping on the stump may induce pain and pressure wound can develop on the skin that covers the bone. Protusion of the bone through the skin is a very serious complication. It is thus obvious that an amputee could not transfer the body weight on the bottom of the stump.
In a normal individual the pressure is distributed over almost the whole foot which constitutes a much wider area than the cross section area of the bone through which the weight is transferred.